US House Speaker Nancy Pelosi, meeting leaders in Taiwan despite warnings from China, said Wednesday that she and other members of Congress in a visiting delegation are showing they will not abandon their commitment to the self-governing island.

“Today the world faces a choice between democracy and autocracy,” she said in a short speech during a meeting with Taiwan’s President Tsai Ing-wen. “America’s determination to preserve democracy, here in Taiwan and around the world, remains ironclad.” China, which claims Taiwan as its territory and opposes any engagement by Taiwanese officials with foreign governments, announced multiple military exercises around the island and issued a series of harsh statements after the delegation touched down Tuesday night in the Taiwanese capital Taipei.

Taiwan decried the planned actions.

“Such an act equals to sealing off Taiwan by air and sea…and severely violates our country’s territorial sovereignty,” said Captain Jian-chang Yu at the National Defence Ministry’s media briefing Wednesday morning.

Pelosi’s trip has heightened US-China tensions more than visits by other members of Congress because of her high-level position as leader of the House of Representatives. She is the first speaker of the house to come to Taiwan in 25 years, since Newt Gingrich in 1997.

Tsai, thanking Pelosi for her decades of support for Taiwan, presented the speaker with a civilian honor, the Order of the Propitious Clouds.

“Facing deliberately heightened military threats, Taiwan will not back down,” Tsai said. “We will firmly uphold our nation’s sovereignty and continue to hold the line of defense for democracy.” Tsai later said in a news conference, “Military exercises are unnecessary responses.” Shortly after Pelosi landed, China announced live-fire drills that reportedly started Tuesday night, as well as a four-day exercise beginning Thursday in waters on all sides of the island.

China’s air force also flew a relatively large contingent of 21 war planes, including fighter jets, toward Taiwan.

Pelosi addressed Beijing’s threats, saying that she hopes it’s clear “while China has stood in the way of Taiwan going to certain meetings, that they understand they will not stand in the way of people coming to Taiwan as a show of friendship and of support”.

Pelosi noted that support for Taiwan is bipartisan in Congress and praised the island’s democracy. She stopped short of saying that the US would defend Taiwan militarily, emphasising that Congress is “committed to the security of Taiwan, in order to have Taiwan be able to most effectively defend themselves”.

Her focus has always been the same, she said, going back to her 1991 visit to Beijing’s Tiananmen Square, when she and other lawmakers unfurled a small banner supporting democracy, two years after a bloody military crackdown on protesters at the square.

That visit was also about human rights and what she called dangerous technology transfers to “rogue countries”.

Pelosi is visiting a human rights museum in Taipei that details the history of the island’s martial law era later Wednesday before she departs for South Korea, the next stop on an Asia tour that also includes Singapore, Malaysia and Japan.

Pelosi, who is leading the trip with five other members of Congress, met earlier Wednesday with representatives from Taiwan’s legislature.

“Madam Speaker’s visit to Taiwan with the delegation, without fear, is the strongest defence of upholding human rights and consolidation of the values of democracy and freedom,” Tsai Chi-chang, vice president of Taiwan’s legislature, said in welcome.

The administration of US President Joe Biden has sought to tone down the volume on the visit, insisting there’s no change in America’s longstanding “one-China policy,” which recognises Beijing but allows informal relations and defence ties with Taipei.

Pelosi said her delegation has “heft”, including Gregory Meeks, chair of the House Foreign Affairs Committee, and Raja Krishnamoorthi from the House Intelligence Committee.

She also mentioned Rep Suzan DelBene, whom Pelosi said was instrumental in the passage of a $280 billion bill aimed at boosting American manufacturing and research in semi-conductor chips – an industry in which Taiwan dominates that is vital for modern electronics.

Reps Andy Kim and Mark Takano are also in the delegation.